A 24-year-old woman remains in a critical condition in the Alice Springs Hospital after she was struck by a vehicle on the Stuart Highway overnight.
Police and emergency services responded to a report of a woman suffering head injuries on the Stuart Highway just after 9pm.
Police declared the area a crime scene and the road was closed for several hours.
A 74-year-old woman presented at the Alice Springs Police Station front counter last night and is currently assisting police with their investigations.
Detectives from the Major Crash Investigation Unit are investigating the timeline of events surrounding the incident.
Police have obtained CCTV footage that captures some of the movements of people and vehicles around this incident, and continue to call for any witnesses travelling south on the Stuart Hwy opposite the Ampol Service station, to contact police on 131 444 or report it anonymously via Crime Stoppers on 1800 333 000.